备忘录模式（Java代码填空）

川长思鸟来 2023-09-27 14:23 70阅读 0赞

package debug01;
    public class debug01 {
        public static void main(String[] args) {
            Originator originator = new Originator();
            CareTaker careTaker = new CareTaker();
            originator.setState("State #1");
            originator.setState("State #2");
            careTaker.add(originator.saveStateToMemento());
            originator.setState("State #3");
            careTaker.add(originator.saveStateToMemento());
            originator.setState("State #4");
            System.out.println("Current State"+ originator.getState());
            originator.getStaterFromMemento(careTaker.get(0));
            System.out.println("First saved State:"+originator.getState());
            originator.getStaterFromMemento(careTaker.get(1));
            System.out.println("Second saved State:"+originator.getState());
        }
    }
    
    package debug01;
    import java.util.*;
    public class CareTaker {
        private List<Memento> mementolist = new ArrayList<Memento>();
    //List在编译器里面了L和l大小写差不多，但记住开头字母一定要大写！！！
        public void add(Memento state) {
            mementolist.add(state);
        }
        public Memento get(int index) {
            return mementolist.get(index);
        }
    }
    
    package debug01;
    public class Originator {
        private String state;
        public void setState(String state) {//不是构造器是一个方法？是的！！构造方法要和类同名且不能有返回值，这明显是类的一个方法。
            this.state = state;
        }
        public String getState() {
            return state;
        }
        public Memento saveStateToMemento() {
            return new Memento(state);
        }
        public void getStaterFromMemento(Memento Memento) {
            state = Memento.getState();
        }
    }
    
    package debug01;
    public class Memento {
        private String state;
        public Memento(String state) {
            this.state = state;
        }
        public String getState() {
            return state;
        }
    }